Sad news Mac gamers: you'll have to wait another few months before you can get your hands on SimCity. The release has been pushed back until August, since Maxis has decided that it is "not ready for primetime yet." With the terrible launch the game had on PC, they are probably being extra careful this time around.
Along with the delay of the Mac version, Maxis posted the patch notes for update 5, which will focus on bug fixes for multiplayer and multi-city games. Since the whole game is unfortunately online all the time, and the cities are so small you always have to have multiple cities, this patch will impact everyone playing. There are also new achievements and regional quests, which is kinda cool I guess.